Update sysctl example (#4800)

docs/examples/customization/sysctl/README.md

@@ -1,9 +1,14 @@
 # Sysctl tuning
 
-This example aims to demonstrate the use of an Init Container to adjust sysctl default values
-using `kubectl patch`
+This example aims to demonstrate the use of an Init Container to adjust sysctl default values using `kubectl patch`
 
 ```console
-kubectl patch deployment -n ingress-nginx nginx-ingress-controller --patch="$(cat patch.json)"
+kubectl patch deployment -n ingress-nginx nginx-ingress-controller \
+    --patch="$(curl https://raw.githubusercontent.com/kubernetes/ingress-nginx/master/docs/examples/customization/sysctl/patch.json)"
 ```
 
+**Changes:**
+- Backlog Queue setting `net.core.somaxconn` from `128` to `32768`
+- Ephemeral Ports setting `net.ipv4.ip_local_port_range` from `32768 60999` to `1024 65000`
+
+In a [post from the NGINX blog](https://www.nginx.com/blog/tuning-nginx/) it is possible to see an explanation for these changes

docs/examples/customization/sysctl/patch.json

@@ -4,11 +4,11 @@
 			"spec": {
 				"initContainers": [{
 					"name": "sysctl",
-					"image": "alpine:3.6",
+					"image": "alpine:3.10",
 					"securityContext": {
 						"privileged": true
 					},
-					"command": ["sh", "-c", "sysctl -w net.core.somaxconn=32768; sysctl -w net.ipv4.ip_local_port_range=1024 65535"]
+					"command": ["sh", "-c", "sysctl -w net.core.somaxconn=32768; sysctl -w net.ipv4.ip_local_port_range='1024 65000'"]
 				}]
 			}
 		}